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By 袁春凤 (Tiffany)
Inspection rules for rubber parts for automobiles
Test method of indentation hardness based on GBT531.1-2008 rubber pocket hardness tester
contents and requirements
Instruments and equipment: Shahr hardness tester (type A, D)
Environmental conditions: the laboratory temperature is 23 C + + 2 C, the relative humidity is 60%~70231
Test method: the specimen thickness is at least 6mm. If the thickness of the sample is less than 6 mm, it can be stacked with no more than 3 layers of smooth, parallel samples with each layer thickness not less than 2 mm. The specimen must have enough area to make the needle and specimen contact position at least 12mm from the edge.
Place the specimen on a solid plane, hold the hardness tester, press the pin at least mm from the edge of the specimen, press the pin smoothly on the specimen, and read it within 3 seconds after the full contact of the pin with the specimen.
Results: the hardness values were measured 5 times at different locations of 6mm, and the median was taken.
Feilong Jiangli will update the more inspection rules for automobile rubber parts
By 袁春凤 (Tiffany)
Rubber shock absorber for automobiles
With the development of social economy, the automobile industry at home and abroad is facing a period of rapid change, which is characterized by further improving the service life of the automobile under the premise of ensuring driving safety, riding comfort, high speed and luxury. Damping products are used to control the vibration and noise of automobiles and to improve their handling stability. They are generally placed in the engine frame, rod holder, suspension shaft lining, center bearing bracket, bump limiter and torsional vibration absorber to improve the safety and comfort of automobiles. Damping products can be divided into four categories: bracket type, shaft lining type, buffer type and damping type. The main requirements of damping, heat resistance and fatigue resistance are good. Automobile shock absorber rubber products include engine bearings, suspension components, rubber springs, rubber air springs and impact rubber protective parts. In recent years, in order to improve the safety, comfort and maneuverability of automobiles, the variety and quantity of shock absorber rubber products for automobiles are increasing as the number of shock absorber rubber products on a car has reached 50-60 pieces.
By 袁春凤 (Tiffany)
Basic knowledge of shock absorbing rubber products
1. Static stiffness: refers to the ratio of the change of pressure (or tensile force) to the change of displacement in a given displacement range. The static stiffness must be measured within a certain displacement range. The static stiffness values measured in different displacement ranges are different, but some families require the change curve measured in the whole displacement range.
2. Dynamic stiffness: It refers to the ratio of the change of pressure (or tensile force) to the change of displacement of damping rubber in a certain displacement range and a certain frequency.
3. dynamic magnification: the ratio of the dynamic stiffness to the static stiffness measured by the damping rubber in a certain range of displacement.
4. Loss coefficient: There is a phase difference between the deformation of rubber and the stress of rubber in the course of the force acting on damping rubber, and the stress of rubber is generally ahead of the phase angle of the deformation of rubber.
5. Torsional stiffness: refers to the ratio of torsional moment to torsional angle of damping rubber within a certain range of torsional angle.
6. Durability: It refers to the number of times of vibration when the rubber is in good condition after n times of reciprocating vibration under certain preloading load, amplitude and vibration frequency in a certain direction.Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department.
By 袁春凤 (Tiffany)
Fatigue life prediction of rubber bushing in vehicle system
1.Response analysis of rubber bushing under random excitation The Monte Carlo method is used to simulate the random excitation spectrum.
2. The fatigue life calculation of rubber bushing under random load can calculate the maximum strain energy density of rubber bushing under different excitation by using the response characteristics of rubber bushing under engine and road excitation obtained previously. The fatigue life of rubber bushing can be calculated under different load conditions. The maximum strain energy density U = 0.5134Nmm2 and the fatigue life N = 771371 were predicted under the excitation of engine speed n = 3000r/min and class B pavement, while U = 0.6893Nmm2, N, = 146774 under the excitation of engine speed n = 3000/min and class D pavement.(Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department.)
3. The test verification of the front sub-frame module is expensive because of the fatigue test of the whole vehicle system. Now the former sub-frame module is the research object, and the calculation results are compared with the test results. The front sub-frame is installed in accordance with its layout in the vehicle, and the six points connected with the body on the sub-frame are restrained. Sinusoidal excitation is carried out at the midpoint of the rear beam, and the maximum frequency which can be reached under the condition of satisfying the amplitude of the force is taken as the test frequency. The amplitude of force is 2.45.2kN. Fatigue failure criteria of rubber bushing: 2mm crack (equivalent to 20% of tensile coefficient).